Implanted hearing aids

ABSTRACT

Several hearing aid configurations for implantation within the middle ear cavity are disclosed. Each hearing aid is minute in size and is joined in operative relationship interiorly of the ear drum to the ossicle bone chain situated within the middle ear cavity. Each hearing aid is characterized by: (1) picking up or &#39;&#39;&#39;&#39;reading&#39;&#39;&#39;&#39; auditory signals off the ear drum, (2) subsequently amplifying and/or transmitting such signals directly to appropriate sound receiving mechanisms, natural or solid-state or both, located on the oval window, the round window, or the promontory leading into the inner ear, and (3) relying upon the automatic gain control (AGC) function performed by the tensors and flexors of the ossicle bone chain to prevent loud sounds from damaging the ear drum.

waited States Patent [19] Branch et al.

[ 4] IMPLANTED HEARING AIDS [76] Inventors: Jack P. Branch, PO. Box17435,

Memphis, Tenn. 381 17; Noel 0. Durham, Charlotte, NC.

[22] Filed: May 19, 1972 [21] Appl. No.: 254,930

Primary Examiner-Ralph D. Blakeslee Att0rneyEric P. Schellin et al.

[57] ABSTRACT Several hearing aid configurations for implantation withinthe middle ear cavity are disclosed. Each hearing aid is minute in sizeand is joined in operative relationship interiorly of the ear drum tothe ossicle bone chain situated within the middle ear cavity. Eachhearing aid is characterized by: l) picking up or reading auditorysignals off the ear drum, (2) subsequently amplifying and/ortransmitting such signals directly to appropriate sound receivingmechanisms, natural or solid-state or both, located on the oval window,the round window, or the promontory leading into the inner ear, and (3)relying upon the automatic gain control (AGC) function performed by thetensors and flexors of the ossicle bone chain to prevent loud soundsfrom damaging the ear drum.

26 Claims, 22 Drawing Figures Patented Oct. 9, 1973 6 Sheets-Sheet 1F/G. lA.

Patented Oct. 9, 1973 3,764,748

6 Sheets-Sheet :3

Patented Oct. 9, 1973 3,764,74g

Patented Oct. 9, 1973 6 Sheets-Sheet 4 F/GZ MIDDLE EAR OUTER EAR AREA A.240;; AUDIO AMPLIFIER CIRCUIT CONTROL LIGHT LIGHT EMITTING DEVICEBATTERY/ Patented Oct. 9, 1973 6 Sheets-Sheet L IMPLANTED HEARING AIDSBACKGROUND OF THE INVENTION 1. Field of the Invention The instantinvention relates to surgically implantable hearing aids for stimulatingthe auditory system of the human body.

2. Description of the Prior Art In recent years the medical arts havebeen, to a large extent, directed to surgical means for the correctionof human bodily defects, i.e., those defects which occur in the humanbody due to injury, congenital malfunction, or the like. Thus, forexample, there have been disclosed in the medical arts a variety ofelements capable of implantation within the human body. These elemeritsin many instances comprise transplanted human organs. In many otherinstances, they comprise artificial members or prosthetic devices, suchas, artificial hearts, heart valves, artificial kidneys, artificiallimbs, and the like.

The population of the United States, as of the date of this invention,is approximately 210,000,000 people. Of such number, approximatelypercent over 30,000,000 persons, have some form of inability toadequately perceive auditory information by means of their auditorysensory powers.

These forms of inability may be classified as follows: first, aconductive loss; secondly, a nerve loss; thirdly, a mixed type lossincluding body nerve and conductive losses; and fourthly, a psychogenicloss.

A conductive loss usually is attributable to excessive calcium orcartilaginous deposits on the joints on the ossicle bone chain of themiddle ear. These deposits restrain movement of the conductive bonechain, and in most instances, also restrict movement of the ovularwindow leading to the inner ear. Other conductive losses may be causedby damage to the ear drum or tympanum through subjection to concussion,extreme atmospheric pressure, or the like. Additionally, the ossiclebone chain may be eroded by chronic infection, congenital conditions, orthe like.

Nerve loss is the most common type of hearing inability. Such loss maybe attributable to deterioration of the auditory nerves throughheredity, disease, noise damage or the like.

The third type of hearing inability, designated above as mixednerve-conductive loss, includes those instances in which an individualhas present in his auditory system a combination of the losses describedabove.

Referring again to condition one, the conductive loss, there are caseswherein the ear drum is eroded, ruptured, or otherwise impaired, and/orthe bone movement is restricted through hardening and malfunction. Thus,in effect, the auditory signals received are reduced in intensity due tothis loss of transmission effectiveness. Therefore, the necessarythreshold level of desirable signals which must be transmitted to thebrain by means of the auditory nerves is not achieved. Consequently, thesignals perceived by the brain are inadequate to allow the brain totranslate such signals into intelligible information.

Referring again to condition two, the nerve loss, it should beunderstood that such nerve damage may occur when fibers of the auditorynerves are damaged through disease or hereditary congenital defects. Thecochlea within the inner ear functions as a receiving mechanism similarto piano keyboard. When the cochlea or any other portion of the auditorynervous system is damaged, only a portion of the auditory energy whichis received thereby is transmitted to the brain. These losses occurparticularly in the upper end of the range of audible sounds, because ofsubjection to industrial noises, jet noises, explosions, atrophy age orthe like.

Certain infectious conditions, such as scarlet fever, measles,sinusitis, or the like, are also known as common causes of the threeabove noted types of auditory losses.

A fourth type of loss, generally designated as psychogenic, usuallyoccurs when there is a loss in energy transmission due to a mentalblockage.

While the present invention is primarily directed to the correction ofthe first three hearing loss conditions described above, it will beunderstood that there may be instances in which the fourth condition maybe corrected or alleviated by the insettion or implantation of thepresent devices.

Each of the above described conditions may be caused by congenitaldefects occurring within the human body, these defects usually beingapparent within two and one-half decades from the birth of theindividual, and at that time, generally perceivable by skilledexamination.

The prior art has disclosed various means for aiding in the correctionof the above-identified and described auditory defects. These correctivedevices have fallen into three basic categories. First, those deviceswhich mechanically direct to the human ear, by means of filtration orthe like, that portion of received auditory oscillations which containintelligible information. Secondly, those devices which convey to theinner ear, via insertion within the outer ear and ear canal or via bonetransmission, electrical and/or mechanical amplification of receivedauditory signals. Thirdly, corrective or prosthetic devices which areintended to be substituted for various elements of the human auditorysystem. Broadly speaking, the implanted transducer of the instantinvention is a hybrid of the second and third categories of correctivedevices.

The ear trumpet is deemed to be representative of the first category ofcorrective devices, for the trumpet merely funnels the sound received inthe outer ear down the ear canal toward the ear drum withoutmechanically or electrically amplifying such auditory energy.

The majority of the hearing aids or corrective devices utilized todayfall within the second category, for such hearing aids rely upon a soundamplifier-transmitter unit carried upon the person, with a wireconnecting the transmitter to a receiver unit which is stuck into theouter ear and extends inwardly into the ear canal. With the advent ofsolid-state electronics, the sound amplifier-transmitter unit has beenmounted in eyeglass frames, earrings, necklaces or the like, with a wireconnection between the eyeglass frames, earrings, necklace, etc., andthe receiver unit inserted within the ear usually through the use of anearmold.

Many persons, however, despite their need for a corrective device toovercome their hearing loss, refuse to wear a hearing aid for estheticor cosmetic reasons. Other persons cannot tolerate the distortions intone caused by the transmission between the amplifiertransmitter unitand the receiver unit, in addition to the distracting buzzing sound ofthe device itself. Furthermore, conventional hearing aids may notprovide effective relief for certain persons since their hearing lossmay be attributable to auditory problems in the mddle ear and/or innerear.

Consequently, an alternative type of corrective device of the secondcategory has been evolved. This corrective device relies upon asurgically planted receiver that conducts auditory energy through thebones of the ossicular chain or the bones of the'skull to the inner ear.The speech amplifier-transmitter, which supplies the power to thereceiver via remote transmission without interconnecting wires, can beencased in a fountain pen shape, cigarette pack shape, standard hearingaid shape or similar object. Although the bone-conductive type ofcorrective device does overcome the widespread esthetic or cosmeticobjection to the more conventional hearing aid, is has not met withcomplete accpetance for numerous reasons. United States Pat. Nos.2,402,392 3,209,081 and 3,346,704, granted to Goldschmidr, Ducote etal., and Mahoney, respectively, disclose illustrative ear implants thatrely upon bone conduction to achieve improved hearing.

As previously noted, there has been constantly increasing attentionfocused upon the utilization of artificial body members or prostheticdevices. Hence, prosthetic stapes of stainless steel, polyethylene,Teflon, platinum or other inert materials that are autoclavable, havebeen fabricated; for example, see US. Pat. Nos. 3,l9l,l88 and 3,196,462,granted to Mercandino et al., and Robinson, respectively.

Such prosthetic devices, which fall within the third category ofcorrective devices as outlined above, enable the recipient of suchimplant to hear in the same fashion as a person with normal hearingability. Thus, the recipient can distinguish sounds clearly over a widerrange of frequencies and with greater fidelity than can be obtained by ahearing aid of the second category for the prosthetic device isoperatively associated with the oval window leading into the inner ear.

One of the major drawbacks of such prosthetic stapes, however, is thatthe hearing loss may be attributable to defects in the malleus, theincus, or the stapes or the oval window area, or any combination ofthese elements. Accordingly, the implantation of the stapes may havelimited success in alleviating hearing losses attributable to diseasesof the middle ear. Furthermore, prior prosthetic stapes are merelysubstitutive in nature and cannot amplify the sound energy received atthe inner ear.

More recently, attempts have been made to surgically implant a hearingaid within the body of the person suffering from a hearing loss. Forexample, US. Pat. No. 3,557,775 granted to Mahoney, discloses theimplantation of a microphone tube, amplifier unit and a speaker tube inthe antrum cell of the mastoid adjacent to the auricular appendage ofthe external ear. The unit is powered by a rechargeable battery, and thesound picked up by the microphone is fed into the speaker tube andthence to a point closely adjacent to the round window leading into theinner ear. The wave motion casued in the inner ear is transmitted to thecochlea, which initiates the electrical impulses to the brain which aretranslated into intelligible sound.

U.S. Pat. No. 3,594,514, granted to Wingrove, also discloses animplantable hearing aid including a piezoelectric ceramic element. Oneend of the element is implanted in an area of the body that can providea stable platform, such as the mastoid bone. The opposite end of theelement is then placed adjacent one of the ossicle bones in the middleear or the oval window leading into the inner ear. The piezoelectriccrystal bends or vibrates in response to avarying voltage signaldelivered thereto over a receiving coil and a related to circuitresponsive to varying sound waves. A microphone preferably locatedexternally to the body. picks up sound waves and changes such waves intomodulated RF signals through appropriate circuitry. The modulated RFsignals are transmitted by a transmitting coil to the above notedreceiving coil, and thence to the piezoelectric crystal.

Whereas Mahoney and Wingrove may suggest ways to resolve some of theproblems previously encountered in designing hearing aids, both patentspick up sound at a point exterior of the middle ear cavity.Additionally, both patents attempt to substitute electronic componentsfor the sound receiving function normally performed with great accuracyby the ear drum and for the sound transmitting function performed by theossicle bone chain. Accordingly, whatever sound receiving andtransmitting capability still resides in one's auditory system may workat cross-purposes to the electronic implant suggested by Mahoney andWingrove. The naturally received sound energy may clash with theelectronically received and transmitted sound energy to producedistortion, and the automatic gain control provided by the tensors andflexors of the ossicle bone chain is totally overlooked.

SUMMARY In light of the magnitude of the problem of hearing losses andin view of the limited success of prior devices in correcting thisproblem, the instant invention contemplates numerous configurations ofimplanted transducers that combine the most desirable features of theseond and third category of corrective devices. More particlarly, theinstant invention contemplates a transducer implanted within the middleear cavity so that it can pick up the sound energy striking the ear drumand can amplify such energy without distortion by causing the ossiclebone chain to mechanically vibrate and transmit such energy to the ovalwindow, round window or promontory leading to the inner ear.Alternatively, in those instances where the ossicle bone chain isdamaged, the instant invention contemplates numerous simple methods forreading the vibrations of the ear drum and translating such vibrationsinto electrical signals for application to the oval window, round windowor promontory leading to the inner ear. Furthermore, the instantinvention relies upon the natural automatic gain control of the tensorsand flexors of the ossicle bone chain to prevent loud sounds frominjuring the wearer to the implant, and also utilizes the naturaldistortion-free transmission of sound through the ossicle bone chainwhenever possible.

Furthermore, the instant invention contemplates surgically drillingthrough the mastoid bone to position the transducer in operativerelationship to the bones of the ossicle chain and/or the oval window,round window or promontory leading into the inner ear while minimizingthe irritation to the ear drum.

Additionally, the implanted transducer constitutes an all-in-the-eardevice and does not require an external, visible interconnection betweenthe amplifiertransmitter and receiver units, thus overcoming the currentwidespread objection to existing unsightly corrective devices because ofcosmetic or esthetic reasons. Furthermore, the implanted hearing aidsminimize, if not eliminate, the distortion and buzzing and may be usedto treat other diseases of the ear, such as tinnitus.

Also the transducer can be fabricated in sundry shapes and from diversematerials that are pre-selected in accordance with the dimension of thebones within the inner ear of the recipient. Ear molds with appropriatetuning and recharging circuits can be utilized to periodicallyexternally re-tune the implanted hearing aid without resorting to asecond operation or surgical procedure. I-Iearing aids utilizing meansfor converting audio impulses into light are also envisioned. Yet,additional significant advantages of the implanted transducer, and thesurgical techniques employed therewith, will become apparent in light ofthe following description of the invention when construed in conjunctionwith the accompanying sheets of drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of thebasic human auditory system;

FIG. 1A is a front elevational view of the osseous labyrinth of thehuman auditory system;

FIG. 1B is a horizontal cross-sectional view of a fragment of thelabyrinth, such view being taken along line 1B-1B in FIG. 1A in thedirection indicated;

FIG. 2 shows a preferred embodiment of the hearing aid implanted inoperative relationship to the ossicle bone chain within the middle earcavity, such hearing aid being sound powered and constructed inaccordance with the principles of the instant invention;

FIG. 3 shows, on an enlarged scale, details of the hearing aid of FIG.2;

FIGS. 4, 5, 6, 7 and 8 show five alternative embodiments of the soundpowered hearing aid;

FIG. 9 shows a hearing aid comprising a transmitting unit and areceiving unit for delivering an electrical stimulus to the inner ear toassist the natural hearing function;

FIG. 10 shows, in schematic fashion, the remotely situated controlcircuitry utilized in conjunction with the various embodiments of thehearing aid;

FIG. 11 shows a firt embodiment of the hearing aid utilizing sensingmeans positioned within the middle ear to read or pick-up the vibrationsof the ear drum when sound strikes such member;

FIG. 12 shows a second embodiment ofa hearing aid utilizing magneticallyresponsive means to read the vibrations of the ear drum;

FIG. 12a is a detaled view of that portion of the embodiment of FIG. 12that is located within the viewing circle;

FIGS. 13-15 diagrammatically show three alternative sensing circuitsthat are responsive to the variations in magnetic field transmitted by amagnet affixed to the ear drum in the manner shows in FIG. 12;

FIG. 16 shows a first, or preferred, embodiment, of a hearing aidutilizing light emitting means; and

FIG. 17 shows, in schematic fashion, the control cir- DESCRIPTION OF THEINVENTION Referring now in detail to the drawings in which similarreference numerals refer to similar parts, FIG. 1 depicts the basicstructure of the human auditory system, such system being indicatedgenerally by reference numeral 10. It is understood that the followingdescription includes only those basic components of the human auditorysystem which are essential to hearing. For further reference to theexact details of the human auditory system, reference may be made to anystandard text, such as The Physics of the Ear" by T.S. Littler,published in I965 by Pergamon Press, Ltd., of London, England; seeparticularly pages 1-14.

The human auditory system comprises the outer ear, indicated generallyby reference numeral 10, and including an auricle II, an auditory canal15 extending inwardly toward an ear drum or tympanum 16; a middle ear 12including therein a malleus 17', an incus I8, and a stapes l9 and aninner ear 13. The bones of the middle ear collectively comprise theenergy transmitting bone chain or ossicle chain 20. These bones aresometimes, respectively, referred to as the hammer 17, the anvil I8, andthe stirrup 15. The stirrup is connected to, in vibratory relation, theovular window or fenestra 30 of a fluid filled sac 40, known as thelabyrinth. The ovular window 30, which is a membrane, separates themiddle ear 12 from the inner car 13.

Referring particularly to 1A, it will be appreciated that ovular window30 forms the entry to the inner car 11, which is enclosed within thelabyrinth. The labyrinth 40 consists of two parts, the membranouslabyrinth and the osseous labyrinth. The membranous labyrinth is asystem of interconnected canals and pouches within the osseouslabyrinth, or protective casing. Consequently, FIG. 1A depicts theconfiguration of the osseous labyrinth, whereas FIG. IB illustrates aportion of the membranous labyrinth. The space between the membranouslabyrinth and the osseous labyrinth is filled with a water-like fluidknown as perilymph. The membranous labyrinth contains another fluidknown as endolymph.

Furthermore, as indicated by the appropriate reference numerals in FIG.1A, the osseous labyrinth is divided into three parts; the vestibule 35,the cochlea 43, and the semi-circular canals 45. There are threesemicircular canals disposed at right angles to another and filled withfluid. These canals regulate the individuals sense of balance and arenot directly involved in the hearing process.

The vestibule 35 is the central part of the osseous labyrinth and thecochlea 43 is that porton of the labyrinth concerned specifically withhearing. The cochlea 43 is snail-shaped and lies horizontally in frontof the vestibule 35. Such spacial relationships can be best understoodby realizing that FIG. ]IA is a front elevational view of the osseouslabyrinth taken on a plane substantially parallel to the plane of eardrum 16 in FIG. I.

As shown by the cut-away section of the cochlea illustrated in FIG. 1B,the membranous cochlea is divided throughout the greater portion of itsspiral length into two passages by the basilar membrane 44. The upperpassage of the membranous cochlea terminates at ovular window 30 whilethe lower passage terminates at round window 42, which is a membranesimilar to ovular window 30. The windows are separated from each otherby promontory 41. The basilar member 44 has alarge number of specializedhair cells 44A disposed thereon; these cells collectively form the organof Corti. These hair cells respond to the sound waves passing throughthe fluid in the cochlea and transmit such sound waves by way ofacoustic nerves 46 to the brain.

The outer ear or auricle 11 serves as a horn for directing soundvibrations into the auditory canal 15, thus impessing these soundvibrations on the tympanum or car drum 16. This member converts suchvibrations to mechanically transmittable energy via the ossicle bonechain 20 thereby transmitting through the midle ear cavity impulsescapable of subsequent translation by the brain. As previously noted,that portion of the human auditory apparatus positioned anteriorly,i.e., towards the source of external auditory energy from the tympanum16, is generally designated as the outer ear 11. The middle ear 12 isoperatively connected to the outer ear 11 through the auditory canal land the tympanum 16. The tympanum serves as the dividing line betweenthe outer car 11 and the middle ear 12.

As explained above, the middle ear l2 incluces a cavity which containstherein the above described ossicle bone chain 20. The bone chain formsa linkage for transmitting sound vibrations from the tympanum 16 tocause mechanical movement for pulsating or vibrating the ovular window30. The stapes is hinged at its upper end at 19a so that the foot plateis pivoted or rocked aganst window 30. In turn, window 30 pulses thefluids in the inner ear 13 to stimulate the organ of Corti and transmitimpulses to the brain via acoustic nerves 46.

Thus, the hearing process can be characterized as a chain reactioninvolving the following four steps. First, sound vibrations are caughtby the external car 11 and passed through auditory canal 15 to thetympanum or ear drum 16. Second, the vibrations of tympanum 16 areconducted by ossicle bone chain 20 to ovular window 30. Third, movementof window disturbs the perilymph between the membranous labyrinth andthe osseous labyrinth, which in turn, disturbs the endolymph within themembranous labyrinth. Lastly, the organ of Corti translates these liquidvibrations into electrical impulses that are transmitted by acousticnerves 46 to the brain.

Referring now to FIGS. 2-8, it will be appreciated that the instantinvention comprises diverse transducers adapted to be implanted orinserted within the human auditory system in operative relationship tothe middle ear structure. Obviously, the present invention is intendedto be so implanted by simple surgical procedures.

Keeping in mind the above description of the basic components of thehuman auditory system, as shown in FIGS. I, 1A and 1B, reference is nowmade to the geometrical configurations, materials and metods forsurgical implantation of the transducers constructed in accordance withthe instant invention.

As explained above, the ear consists of an outer ear portion 10, amiddle ear portion 12, and an inner portion 13. Contained within themiddle ear portion 12, whose boundaries are roughly defined by thetympanum l6 and the ovular window 30, there is the ossicle bone chainconsisting of the hammer I7, anvil I8, and stirrup 19. The stirrup, inthe normal human auditory system, is in operative mechanical vibratoryrelationship to the ovular window 30. All of these elements arecontained within the middle ear cavity and operate in the mannerdescribed above to coact with the other above-described members of thehuman auditory system. Tensor muscles 16b are disposed within the cavityto maintain the tympanum l6 properly tensioned, as shows in FIGS. 2, 4and 5-8, and the chorda tympanum 16a maintains the bone chain 20 inproper orientation. Flexors 16c are also shown in FIGS. 2, 4 and 5-8;the tensors and flexors work in concert with each other to prevent loudnoises from damaging the ear drum I6 and the other members of theauditory system.

Referring now to FIGS. 2 and 3, a preferred embodiment of the hearingaid is implanted in the middle ear cavity and is identified generally byreference numeral 60. The stapes has been removed from the ossicle bonechain, either through a simple surgical procedure or throughdeterioration attributable to diseases of the auditory system.

Hearing aid 60 includes a stylus 62 with an annular upper end 64 with aslot 66 passing therethrough; the slot enables stylus 62 to be slippedonto, and retained in position upon, anvil 18 by applying a crimpingpressure to end 64. The point of the stylus bears against the base of apressure sensitive device 68. A suitable pressure sensitive device isthe Pitran piezojunction transducer produced by Stow Laboratories, Inc.of Hudson, Massachusetts; such transducer assumes the form of a planarNPN transistor in which the emitter-base junction is responsive to theapplication of a pressure or a point force to produce a linear,amplified voltage. Nu-

merous other pressure sensitive devices could be utilized in place ofthe Pitran piezoelectric transducer; such devices include piezoelectriccrystals, diodes, strain gage transducers or electrically conductivewires.

The variable voltage generated by the variable pressure upon device 68is conducted by appropriate lead 70 to remotely situated tuning circuit72. Circuit 72, which is encased in a suitable housing, is implanted inthe mastoid bone near auricle or outer ear 11. A representative circuit72 may include a high gain FET circuit with automatic gain control toprovide external volume tuning for implant 60. The variable amplifiedvoltage signal is conducted over lead 74 to one side of a pair ofpiezoelectric crystals retained between the bottom face of pressuresensitive device 68 and oval window 30. The crystals may be orientedeither horizontally, as shown in FIG. 3, or vertically, as shown in FIG.4. The signals are impressed upon the crystals, which may be benders,stretchers, twisters, or combinations thereof, and the crystals vibrateagainst or in proximity to the oval window 30 or cochlea 43.

Although the pressure of the stylus upon the pressure sensitive device68 may produce sufficient voltage to effectively vibrate the crystalsagainst oval window 30, an auxiliary power source may be utilized toinsure sufficient voltage for efficiently vibrating the crystals for aprolonged period of time. The auxiliary power source, which isdesignated by reference numeral 80, may assume the form of a minuterechargable nickelcadmium battery or other suitable rechargableminiature power supply; power source may also be implanted in themastoid bone at a location remote from the middle ear cavitity. Acharging circuit 82 is operatively associated with power supply 80 andcould be encased in the same housing implanted in the mastoid bone.Power supply 80 and charging circuit 82 are operatively associated withtransducer 68 and crystals 76,

78 by leads 84 and 86. The voltage from power supply 80 is impressedupon the crystals via lead 86, and tuning circuit 72 adjusts thefrequency at which the crystals will deform or vibrate.

FIG. 4 showsthe first alternative embodiment of the instant implanted,sound powered hearing aid. The term sound powered indicates that the eardrum is intact and that the vibrations from the sound striking same aretransmitted mechanically through the ossicle bone chain toward the innerear. It will be noted that the hearing aids shown in FIGS. 2, 4, 5, 6, 7and 8 fall within the broad category of sound powered devices.

In the embodiment of FIGS. 2 and 3 the piezoelectric crystals arehorizontally oriented whereas in the embodiment of FIG. 4, identicalcrystals are vertically oriented in operative relationship to ovalwindow 30; the

stapes or stirrup 19 has not been removed from the ossicle bone chain,and no external control circuits are utilized. The crystals are situatedin operative relationship to the footplate of stapes l9 and thevibrations of the crystals assist the footplate in rocking the stapesabout hinge point 19. By virtue of leaving the ossicle bone chainintact, the auditory energy striking the ear drum and passing throughthe bone chain is distortionfree and hearing aid 88 need only supplyminimal assistance to the hearing process. Aid 88 is well suited forovercoming mild hearing losses. Alternatively, the stapes 19 can beremoved and the aid 88 placed in its place where conditions permit;consequently, stapes 19 is shown in dotted outline in FIG. 4.

FIG. shows a second alternative sound powered hearing aid 92 that islocated within the middle ear cavity in operative relationship to theossicle bone chain. As in the embodiment of FIGS. 2 and 3, the stapes isremoved from the ossicle bone chain, thus allowing the end of incus 18to be free hanging. Hearing aid 92 includes an elongated piezoelectriccrystal bar 94 that is clipped onto the free end of incus 18 by means ofcrimpable rings 96, 98. A pin or stylus 100 is secured to the lower endof bar 94 and extends inwardly into contact with pressure sensitivedevice 102 situated in proximity to a crystalline device 103 situated onpromontory 41, adjacent to, or near, oval window 30. Pressure sensitivedevice 102, which may be a Pitran piezoelectric transducer, apiezoelectric crystal, a pressure sensitive diode, a strain gagetransducer or the like produces a voltage that stimulates the ovalwindow 30, and/or the cochlea 43, thus raising the threshold of hearing.Crystalline device 103 may be a bucker, bender, or twister crystal, orcombinations thereof.

In addition to serving as a part of the mechanical linkage that producesa significant mechanical advantage in transmitting forces from ear drum16 to oval window 30, the stresses placed upon pressure sensitive device102 produce a variable voltage which is conducted by lead 101 to aremotely situated, high gain amplifying circuit 104. The frequency ofthe voltage is adjusted to the desired rate by circuit 104 and is thenreturned over lead 105 to crystal 103 to cause same to vibrate or deformat the selected frequency.

Although the pressure upon the pressure sensitive device 102 may producesufficient voltage to effectively vibrate crystal 103 against ovalwindow 30, an auxiliary power supply 106 may be connected over leads107, 109 to opposite faces of crystal 103. Furthermore, a chargingcircuit (not shown), similar to charging circuit 82 of FIG. 3, could beimplanted in the mastoid bone in operative relationship to auxiliarypower supply 106.

Since bar 94 is a piezoelectric crystal, a variable voltage is alsoproduced at opposite faces thereof when it is mechanically stressed bythe ossicle bone chain. Such voltage may be added to the voltageproduced by the pressure sensitive device 102 and the auxiliary powersupply 106, and the sum of the voltages may be applied to crystal 103for more efficient operation.

A diode could be utilized in lieu of the crystalline device situated inproximity to oval window 30 in the hearing aid embodiments of FIGS. 2-5.Such diode would receive the voltage produced by pressure sensitivedevice 68 and rectify same into pulsating D.C. voltage that could beapplied directly to the oval window, thus providing electrical stimulusto the auditory nerve. Alternatively, the diode and the crystallinedevice could be omitted, and the voltage from pressure sensitive device6'8 could be led over electrically conductive wires directly to the ovalwindow to shock same.

FIG. 6 shows a third alternative embodiment of the sound powered hearingaid, such embodiment being indicated generally by reference numeral 108.The ossicle bone chain is intact, and hearing aid 108 assumes the formof a pressure sensitive device of substantially rectangular shape with asmall stylus bearing thereagainst. One corner of the pressure sensitivedevice is secured to the footplate of stapes 19 to assist the stapes inrocking or pivoting against window 30 about hinge 190. The pressuretransmitted through the ossicle bone chain presses against the stylus ofdevice 108 with sufficient intensity to generate a voltage on leads 109that stimulate the area of oval window 30. If need be, additionalvoltage may be supplied to pressure sensitive device 102 from a remotepower supply situated in the mastoid bone near auricle 11.

FIG. 7 shows a fourth alternative embodiment of the sound poweredhearing aid, such embodiment being indicated generally be referencenumeral 1 10. The stapes has been removed from the ossicle bone chain,so that the inwardly extending, free end of anvil 18 can be utilized totransmit vibrations from the ear drum to hearing aid 110. A collar 112on hearing aid is slipped over the free end of anvil 18, so that themovement of the anvil causes movement of stylus 114 situated on theunderside of collar 112. The stylus bears upon a pressure sensitivedevice 116, such as the Pitran transducer described above, and producesa voltage proportional to the force pressing thereagainst. The voltageis led over appropriate leads 118 to a remotely situated tuning circuit119 and/or an auxiliary power source 121. The voltage after appropriatetuning andlor amplification, is returned via leads 120 to opposite facesof a crystalline device 122, such as a piezoelectric crystal. Thecrystal rests atop a fluid filled sack 124 that is secured to ovalwindow 30 by a layer 126 of plastic jelly-like foam known commerciallyas .Iel-Foam.

Consequently, sound striking the ear drum and passing through the hammerto the free end of the anvil, produces a variable pressure bearingagainst pressure sensitive device 116. Device 116, in turn, generates avoltage proportional to the pressure applied thereto; the voltage is ledover leads 118 to the remote tuning and/or amplification circuits 119and 121, respectively, and then returned over leads 120 for applicationto the opposite faces of crystal 122. The crystal, which may be abender, twister, or bucker, or any combination thereof, flexes and suchmovement is transmitted through the fluid medium in sack 124 to ovalwindow 30.

If desired, sack 124 may be designed as a truncated cone with thebroader surface providing increased support for crystalline device 122.The parallel, narrower surface would be affixed to oval window 30. Thecone shape of the sack might well enhance the effectiveness of thevibrations transmitted therethrough. Additionally, the voltage producedby pressure sensitive device 116 may be amplified, tuned, clipped, etc.,by conventional circuits before being applied to crystal 122.

FIG. 8 shows a fifth alternative embodiment of the sound powered hearingaid, such embodiment being indicated generally by reference numeral 125.Hearing aid 125 is similar to the hearing aid 110 of FIG. 7 and includesa collar 126, a stylus 128, a pressure responsive device 130, leads 132and 134, control circuits 136 and 138, crystalline device 140, and afluid filled sack 142 positioned atop oval window 30. While hearing aid1 in FIG. 7 requires the removal of stapes 19, hearing aid 125 takesfull advantage of the ossicle bone chain and leaves same intact.

Pressure sensitive device 130, which is a minute element, is slippedbetween anvil l8 and stirrup 19 at their juncture, and sack 142 ispositioned between the footplate of stirrup l9 and oval window 30. Themovement of the inner end of anvil 18, in response to sound striking theear drum, thus presses stylus 128 against pressure responsive device 128to produce a variable voltage output across leads 132, 134. The variablevoltage is tuned by control circuit 136, and the variable voltage isamplified by control circuit 138. The voltage is then applied across theopposite faces of crystalline device 140, and the resultant movement ofdevice 140 is transmitted by sack 142 to oval window 30. The sack may beadhered to the oval window by a suitable surgically acceptable jelly, orthe depth of the oval window with respect to promontory 41 may be suchthat the sack is retained in place, without adhesive, by the surroundingwalls of the promontory. The sack and the pressure sensitive device aredesignated to take up any slack in the ossicle bone chain, and thusmaximize the effectiveness of the sound conduction through the ossiclebone chain.

Variants of hearing aid 125 are equally feasible. For example, sack 142may be omitted and crystalline device 140 may be positioned against ovalwindow 30. Alternatively, crystalline device 140 may be implanted in themastoid bone surrounding the middle ear cavity and rely upon boneconduction techniques to send sound into the inner ear. Additionally,the pressure sensitive device may be slipped under the footplate ofstapes 19 to take advantage of the rocking motion of the stapes. As yetanother variant, a first pressure sensitive device may be slippedbetween teh anvil l8 and the stirrup l9, and a second device may beslipped beneath the footplate. In all instances, such hearing aids 125are particularly effective in overcoming hearing deficienciesattributable to conductive losses.

Although the operation of hearing aids 60, 88, 92, 108, 110, and 125 hasalready been described in detail above, it is believed to be expedientto briefly reiterate the salient features of such hearing aids at thisjuncture. In all embodiments, sound passing down ear canal l5 andstriking ear drum 16, is, in normal sequence, amplifled twenty-two timesby the fulcrum action of the ossicle bone chain before reaching ovalwindow 30. The

stylus or the pin function in the same capacity as the stapes withoutany reduction in the mechanical amplification. Furthermore, the tensorsand flexors function as a natural automatic gain control circuit tocushion the impact of loud sounds upon the auditory system.

Additionally, in all the above described soundpowered embodiments,either the stapes 19 or the stylus that cooperates with the pressuresensitive device, converts the movement of the ear drum and the ossiclebones to movement of the pressure sensitive device positioned over, orin operative relationship, to oval window 30. The varied pressure of thesound striking the ear drum thus produces a varied output voltage thatmay be fed directly to oval window 30 for electrical stimulus, or may beamplified and then impressed upon a crystalline device, such as apiezoelectric crystal, adjacent to, or atop, the oval window. Externaltuning and volume control circuits may also be utilized. In summary, theear drum and the ossicle bone chain replace the microphone in thereceiving unit of conventional hearing aids, for the sound from the eardrum is mechanically amplified through the natural functions of theossicle bone chain; such variations in the bone chain are pressed upon apressure sensitive device to produce a correspondingly varied electricaloutput that is sent to a high gain amplifying circuit and then to acrystalline device operatively associated with the oval window.Alternatively, the high gain amplifying circuit may be omitted. Theabove described hearing aids are considered to be sound powered devices,and will probably correct one-half of the mild hearing losses.Approximately, per cent of those persons suffering from hearing lossesfall within this extremely broad category.

In all of the embodiments of the instant hearing aid, the crystallinedevices, diodes and conductive wires (see FIG. 9) are described andillustrated for the sake of clarity as if they were in direct contactwith oval window 30 or promontory area 41. However, the actualimplantation of the hearing aids has shown that an alternative method offixation is more desirable. Such method relies upon a pliable substance,such as a Jel Foam, to be packed about the innermost end of the deviceto be coupled to oval window 30. The pliable substance dissolvespartially and leaves a protective sac of minute dimension, the sacfunctioning in much the same manner as a balloon loosely filled withwater. This resilience helps to adjust the linkage differential in thebone displacement of the ossicle bone chain. The sac also reduces thedanger of rupturing the oval window, and does prevent electrical shockor stimulus from passing therethrough to the oval window.

FIG. 9 shows a hearing aid that delivers an electrical stimulus to ovalwindow 30, such hearing aid comprising two units, a first, ortransmitting unit 144 and a second, or receiving, unit 146. Unit 144,which is encased within plastic housing 148 and has an outwardlyextending pull tab 150, is situated within ear canal 15. Unit 144includes a microphone 152, such as an electret microphone, a battery 154or other suitable power source; a volume control circuit 156; and atransmitting coil 158. Transmitting coil 158 can radiate RF energy ormagnetic vibrations through the skin to energize receiving unit 146.

Unit 146, which is implanted just beneath the skin in the mastoid bonedefining the ear canal, includes a receiving coil 160, a conducting wire162, and an electrically stimulated device 164 affixed to promontory 41between the oval and round windows leading into the inner ear. Device164 may be a piezoelectric crystal, a diode or may merely be acontinuation of conducting wire 130. In all instances, the electricstimulation cooperates with the natural functioning of the ossicle bonechain to increase the hearing of the wearer of this two unit hearingaid.

FIG. shows a pressure sensitive device 166 and an actuating button ordiaphragm 168 positioned immediately adjacent thereto. The button isimplanted just under the skin behind auricle l l. The pressure sensitivedevice may well be a Pitran transducer of the type discussed above, sothat manual pressure applied to button 168 will press the stylus 170postioned therebelow against the transducer and produce a variablevoltage. Such voltage can be fed into the implanted battery or powersource 172 to recharge same, whenever needed. A second button 174 and asecond pressure sensitive device 176 can produce a voltage to be fed tovolume control circuit 178; when such circuit is sensitive to voltagelevels. If circuit 178 is not so responsive, button 174 and secondpressure sensitive device 176 can be omitted without serious impairmentto the efficiency of the implanted hearing aid.

FIG. 11 shows a first, or preferred, embodiment of a hearing aid thatutilizes transmitting means secured to the inner side of ear drum 16 totransmit signals through the air in the middle ear cavity to sensingmeans disposed adjacent to the oval window 30, promontory 41, or roundwindow 42. Whereas the sound powered embodiments of FIGS. 2-9 utilizemechanical transmission of sounds through the ossicle bone chain, andthe embodiment of FIG. 10 relies upon electrical stimulation, theembodiments of FIGS. 11-17 focus primarily upon transmission between theear drum and implanted sensing means and pay only incidental attentionto the sound mechanically transmitted through the ossicle bone chain.

The hearing aid of FIG. 11 is identified generally by referencecharacter 180 and includes a small transmitter 182 which assumes theform of a charged piece of material on the inner side of ear drum 16;the transmitter may be a magnet, a fragment of phosphor, a radio activeisotope or a charged particle. The receiving unit includes either anelectret microphone 184, a magnetic diode, or a transistor gate that issensitive to magnetic variations, and a piezoelectric crystal 186positioned in the area of promontory 41. The electret microphone mightbe one-eighth inch in diameter, and can be obtained from BellLaboratories and numerous other commercial sources; the magnetic diodesare also available from similar sources. It will be noted that theossicle bone chain can be left intact while utilizing hearing aid 180.

The negatively or postively charged piece of material 182 serves to varythe output of electret microphone 184. The electret in microphone 184has a static potential, and the plus or minus charge held by piece 182will repel, or attract, the electret at the same rate that sound isstriking drum 16. The minute voltage variations produced by the electretare sent via appropriate leads (not shown) to a remotely situated highgain amplifier circuit 188; after suitable amplification, the voltage isreturned over lead 190 and is impressed upon crystal 186 situatedadjacent to oval window 30 to cause same to vibrate. Additionally,hearing aid 180 may employ a remotely located power source 192 with, orwithout, a remote volume control circuit; the power source and thevolume control are implanted in the mastoid bone at locations removedfrom one another. Both power source 192 and high gain amplifier circuit188 (if such circuit employs a PET or other magnetic responsive device)are recharged by magnetic induction in a manner that has already beenexplained in connection with FIG. 10. A reed switch 194 is inserted intothe circuitry of FIG. 11 to cut off the power to crystal 186 while thebattery or power source 192 is being recharged.

FIG. 12 shows an alternative form of hearing aid, designated generallyby reference numeral 196, that relies upon transmitting means affixed tothe inner side of the ear drum and sensing means disposed adjacent tothe oval window 30, promontory 41, or round window. The distance betweenthe transmitting means on the eardrum and the sensing means on thepromontory is approximately one-quarter' of an inch; obviously,effectively bridging such a small distance without transmission loss ordistortion is a relatively simple task for existing solid-state devices.

Hearing aid 196 includes a first minute magnet 198 with a hook 200 thatis slipped over the malleus or hammer 17 near its point of contact withthe inner face of ear drum 16. Hook 200 might also be anchored in thevicinity of chorda typanum 16a; see FIG. 1. Continuing interiorlythrough the middle ear cavity, hearing aid 196 further includes a secondmagnet 202 that is operatively associated with a stylus 204 affixed todiaphragm 206. The stylus is positioned in operative relationship to apressure sensitive device 208, such as a Pitran transducer, whichproduces a variable voltage proportional to the pressure applied theretoby the stylus. The voltage output from device 208 is led over leads 210and 212 to a remote tuning and amplifying circuit 212 and a remotecharging circuit 214, respectively. The output from control circuits 212and 214 is applied to crystalline situated in the area of promontory 41,which device may be a piezoelectric crystal capable of bucking, twistingor bending. Under certain circumstances control circuits 212 and 214 maybe omitted. In either event, the motion of the crystalline device isrelated directly to the sound striking ear drum l6 and the ossicle bonechain is left intact, thus leaving the natural automatic gain control(AGC) facility of the ossicle bone chaim unimpaired.

FIG. 13 diagrammatically shows another sensing circuit that will respondto the variations in the magnetic field transmitted thereto by magnet198. The circuit of FIG. 13 also includes the second magnet 202 which issecured to the diaphragm 218 of an electret microphone 220. The movementof magnet 198 as sound energy strikes the ear drum causes magnet 202 tomove in response to changes in the magnetic field establishedtherebetween. The movement of magnet 202 pumps electret microphone 220and produces a variable voltage output that is led, over appropriateleads, to remote tuning circuit 222 and remote charging circuit 224.After the voltage has been properly regulated, it is applied tocrystalline device 226, which vibrates in the area of promontory 41.

FIG. 14 diagrammatically shows another sensing circult that will respondto the variations in the magnetic field transmitted thereto by magnet198 affixed to the inner side of the ear drum. The second or receivingmagnet 202 utilized in the ambodiments of FIGS. 12 and 13 is replaced bya transistor gate 228 that is responsive to changes in the intensity andpolarity of magnetic fields; one common type of gate 228 is afieldeffect transistor (F E.T.). The small output voltage across gate228 is suitable regulated by control circuits 222, 224, before beingapplied to a crystalline device 229 situated in the area of promontory41.

FIG. 15 diagrammatically shows yet another sensing circuit that willrespond to the variations in the magnetic field transmitted thereto bymagnet 198 affixed to the inner side of the ear drum. The second orreceiving magnet 202 utilized in the embodiments of FIGS. 12 and 13, orthe transistor gate 228 of FIG. 14, is replaced by a Hall-effect device231) that is responsive to changes in the intensity and polarity ofmagnetic fields. The small output voltage across device 230 is suitablyregulated by control circuits 222, 224 before being applied to acrystalline device 231 situated in the area of promontory 41.

Numerous modifications can readily be effectuated in the hearing aiddepicted in FIGS. 12-15. For example, a small fragment of phosphor orother radio-active isotope could be substituted for magnet 198. Also,crystalline devices 216 and 226 (FIGS. 12 and 13, re spectively) couldbe eliminated, and the variable voltage appearing across the receivingmeans could be utilized directly to stimulate, or shock, the ovalwindow, promontory, or round window. Alternatively, the crystallinedevices could be eliminated and a diode substituted therefore; suchdiode would receive the voltage produced by the sensing means andrectify same into pulsating DC. voltage that could be applied directlyto oval window 30, thus providing electrical stimulus to the auditorynerves of the inner ear.

FIGS. 16-17 disclose a two unit hearing aid that employs an audioresponsive light emitting unit and light sensing means on opposite sidesof the ear drum that respond to sounds striking the ear drum. The audioresponsive unit is identified by reference numeral 230 and is encased ina plastic housing 232 that fits within ear canal 15; the housing has apull tab 234 for removing the unit. Within housing 232 is a miniaturemicrophone 236, a long-lived rechargable battery 238, an amplifier 240and a circuit 242 for energizing light source 244 that extends throughthe housing and emits a beam of collimated light down the ear canal.

The light sensing means is disposed on the opposite side of ear drum 16in the area of promontory 41 and in substantial alignment with lightsource 244. The light sensing means includes a light responsive resistor246 connected to an amplifier 248, the output of such amplifier beingfed to remote control circuits 250, 252 and thence to crystalline device254. A suitable resistor 246 would be a cadmium sulphide cell orphotocell or a selenium cell. The vibration of device 254 in the area ofpromontory 41 augments the sound energy mechanically transmitted fromthe ear drum through the ossicle bone chain. If desired, crystallinedevice 254 could be omitted and the output voltage from amplifier 248could be impressed directly upon the area of promontory 41 toelectrically stimulate the auditory nerves. Alternatively, crystallinedevice 254 could be omitted and the output voltage from amplifier 248could be fed to a diode that would convert the voltage into a pulsatingD. C. stimulus.

The transmitting unit 230 converts the sound or audio energy strikingmicrophone 236 into light pulses emanating from light source 244. Sinceear drum 16 is opaque and the ear canal is dark, the light pulses areeasily detected by diode 246 and the circuitry associ ated therewith forconverting the light energy into electrical energy.

FIG. 18 shows yet another embodiment of a hearing aid constructed inaccordance with the principles of the instant invention. This embodimentalso comprises two units, a first or transmitting unit 256, and a secondor receiving unit 258. Unit 256, which is encased within plastic housing260 and has an outwardly extending pull tab 262, is situated within earcanal 15. Unit 256 includes a microphone 264 for receiving auditoryenergy, a battery 266 or other suitable power source, an amplifyingcircuit 268, and a transmitting device 270, such as a coil. Unit 258comprises a receiver 272 operatively associated with a small,rechargeable battery 274 and a crystalline device 276. The receiver, thebattery and the crystalline device are implanted within the mastoid bonea short distance from ear canal 15. Unit 256 sends RF, magnetic orelecrostatic signals to implanted receiving unit 258. Unit 258 thenconverts the signal into vibratory movement of crystalline device 276;such movement is transmitted to the cochlea by bone conduction throughthe mastoid bone.

The hearing aid embodiment of FIG. 18 is particularly well suited toovercome tinnitus, a physical and/or mental disease associated with theauditory system that produces a sensation of ringing, whistling orbuzzing in the ears of the person so afflicted. The transmitting unitscan be removed from the ear canal and tuned so as to transmit varioussounds to the ear nerve, the characteristics of the transmitted soundbeing selected so as to mask the unpleasant sounds associated withtinnitus.

FIG. 19 illustrates an ear mold 278 that fits into auricle 11 andextends into ear canal 15 towards ear drum 16. Ear mold 278, which maybe utilized in connection with the manually operable recharging devicesof FIG. 10 or in lieu thereof, is a custom-made, hollow shell with afirst charging coil 280 secured therein in a fixed position consistentwith the fixed position of implanted power source 172 which has areceiving coil 173. Charging coil 280 radiates energy to coil 173 forimplanted power source 172 to thereby recharge same. A second chargingcoil 282 may be used to adjust the implanted volume and/or frequencytuning circuit 178; however, care must be exercised to position thecoils as far apart as space will permit, thus isolating the coils andcircuits from one another.

A charging magnet 284, or other polarizing device, is situated at theinnermost end of ear mold 278, which is reduced in diameter to avoiddiscomfort to the person temporarily wearing same during the fittingprocess. The charging magnet or polarizing device causes variations inthe polarity and intensity of the magnet or radioactive fragmentattached to the inner side of ear drum 16, as shown in FIGS. 11-15. Thecharging coils 280 and 282 in ear mold 278 are powered over appropriateleads from a remote, adjustable control device 284 that is simplyplugged into a conventional wall outlet.

At periodic intervals, the wearer of the hearing aid will visit a clinicand have the ear mold inserted into his ear. Trained personnel will thenreadjust the control circuits for the hearing aid without resort tosurgical procedures.

Many of the above described hearing aids can be implanted in the firstinstance by the simple surgical procedure of cutting and laying back theear drum to expose the middle ear cavity. Other hearing aids can beimplanted by drilling through the mastoid bone behind the ear toward themiddle ear cavity; an accurately drilled hole will be aligned with thearea of the oval window 30, promontory 41 and the round window so thatthe various sensing devices can be positioned thereagainst. Drillingthrough the mastoid leaves the ear drum intact and reduces the potentialside-effects of such initial surgical procedure.

Since sundry additional modifications may be made in the configurationand materials of the instant implanted hearing aids, it is to beunderstood that all matter herein set forth or shown in the accompanyingdrawings is to be interpreted as illustrative in nature and not in alimiting sense.

We claim:

1. An implantable, sound powered hearing aid comprising:

a. transducer means positioned interiorly of the ear drum in proximityto the oval window within the middle ear cavity,

b. said transducer means being pressure sensitive so as to generate avariable voltage output in response to the application of pressurethereto,

c. stylus means secured to either the hammer, anvil or stirrup of theossicle bone chain located inthe middle ear cavity in operativerelationship to said pressure sensitive transducer means, said stylusmeans being pressed against said transducer means by the ossicle bonechain with a variable force when sound strikes the ear drum to therebyproduce a variable voltage, and

e. conducting means to lead said variable voltage to the area of theoval window to electrically stimulate same.

2. The hearing aid as defined in claim 1 further including apiezoelectric crystal positioned in the area of the oval window, saidconducting means impressing said variable voltage upon said crystal tocause same to vibrate and thus stimulate the auditory nerve.

3. The hearing aid as defined in claim 1 further including a diodepositioned in the area of the oval window, said conducting means leadingsaid variable voltage to said diode which rectifies same into pulsatingD. C. voltage and thus stimulates the auditory nerve.

4. The hearing aid as defined in claim 2 further including an amplifyingcircuit connected between said pressure sensitive transducer means andsaid piezoelectric crystal, said amplifying circuit amplifying thevariable voltage produced by said transducer means before said voltageis impressed upon said crystal.

5. The hearing aid as defined in claim 2 further including an auxiliarypower supply, connected to said piezoelectric crystal, to impress itsvoltage thereupon.

6. The hearing aid as defined in claim 5 further including a tuningcircuit connected between said pressure sensitive transducer means andsaid piezoelectric crystal and in operative relationship to said powersupply, said tuning circuit adjusting the frequency at which saidcrystal will vibrate.

7. The hearing aid as defined in claim 5 further including rechargingmeans for said auxiliary power supply, said recharging means comprisinga button under the skin of the wearer of the hearing aid, a stylussecured to said button, and a pressure sensitive transducer meanssituated in operative relationship to said transducer means, saidtransducer means connected to said auxiliary power supply to supply avariable voltage thereto, said button being manually depressed to pressthe stylus against the transducer means whenever said auxiliary powersupply requires recharging.

8. The hearing aid as defined in claim 2 wherein said stylus meanscomprises a piezoelectric bar with a pin extending outwardly therefrom.

9. The hearing aid as defined in claim 8 wherein said piezoelectric barproduces a variable voltage as said bar is stressed when sound strikingthe ear drum is transmitted through the ossicle bone chain, and circuitmeans for amplifying the variable voltage before applying same to theoval window area.

10. The hearing aid as defined in claim 1 wherein the transducer meansare held in a rectangular package, said package being positioned in theopening of the stapes of said ossicle bone chain with one corner of thepackage bearing against the footplate of the stapes.

11. The hearing aid as defined in claim 1 further including a resilientfluid filled sack interposed between the ossicle bone chain and the areaof the oval window and a piezoelectric crystal disposed thereupon, saidconducting means impressing said variable voltage produced by saidpressure sensitive device upon said crystal which vibrates atop the sackand transmits said vibrations therethrough to the area of the ovalwindow.

12. The hearing aid as defined in claim 11 further including a collarsituated atop said transducer means, said collar engaging the free endof the anvil of the ossicle bone chain.

13. The hearing aid as defined in claim 1 wherein said transducer meansand said stylus means are slipped between the joint formed by the anviland stirrup of the ossicle bone chain.

14. An implanted hearing aid comprising:

a. a transmitting unit encased in a housing and positioned within theear canal, said transmitting unit including:

1. a miniature microphone for producing a variable voltage proportionalto the sound striking same,

2. a power source for energizing said microphone,

3. an amplifying circuit for increasing the voltage produced by saidmicrophone,

4. a transmitting coil operatively connected to said microphone, saidpower source, and said amplifying circuit for radiating anelectromagnetic field of variable intensity, and

b. a receiving unit including:

1. a receiving coil implanted in the mastoid bone in proximity to saidtransmitting coil, said coils being inductively coupled together, and

2. conducting means implanted in the mastoid bone to lead the variablevoltage received by said coil to the area of the oval window toelectrically stimulate same.

15. The hearing aid as defined in claim 14 further including apiezoelectric crystal positioned in the area of the oval window, saidconducting means impressing said variable voltage upon said crystal tocause same to vibrate and thus stimulate the auditory nerve.

16. The hearing aid as defined in claim 14 further including a diodepositioned in the area of the oval window, said conducting means leadingsaid variable voltage to said diode which rectifies same into pulsatingD. C. voltage and thus stimulates the auditory nerve.

17. An improved hearing aid comprising:

a. transmitting means secured to the inner surface of the eardrum in thearea of the junction defined by the hammer and the ear drum, saidtransmitting means radiating magnetic waves into the middle ear cavity,

b. receiving means situated within the middle ear cavity on thepromonotry promontory the area of the oval window, said receiving meansincluding: 1. magnetically responsive means retained upon a flexiblediaphragm,

2. a stylus connected to said diaphragm,

3. a pressure sensitive transducer for producing a variable voltage inresponse to the application of pressure thereto, said stylus beingpositioned in operative relationship to said transducer,

4. said stylus being pressed against said transducer when thetransmitting moves relative to the receiving means as sound energystrikes the ear drum to thereby produce a variable voltage, and

c. conducting means to lead said variable voltage to the area of theoval window to electrically stimulate same.

18. The hearing aid of claim 17 wherein the transmitting means is apermanent magnet.

19. The hearing aid of claim 17 wherein the transmitting means is afragment of phosphor.

20. The hearing aid as defined in claim 17 wherein the transmittingmeans is a radioactive isotope.

21. The hearing aid as defined in claim 17 wherein the magneticallyresponsive means is a field-effect transistor gate.

22. The hearing aid as defined in claim 17 wherein the magneticallyresponsive means is a Hall-efiect element.

23. The hearing aid as defined in claim 17 further including apiezoelectric crystal positioned in the area of the oval window, saidconducting means impressing said variable voltage upon said crystal tocause same to vibrate and thus stimulate the auditory nerve.

24. The hearing aid as defined in claim 17 further including a diodepositioned in the area of the oval window, said conducting means leadingsaid variable voltage to said diode which rectifies same into pulsatingD. C. voltage and thus stimulates the auditory nerve.

25. An implanted hearing aid comprising:

a. a transmitting unit encased in a housing and positioned within theear canal, said transmitting unit including:

l. a miniature microphone for producing a variable voltage proportionalto the sound striking same,

2. a power source for energizing said microphone,

3. an amplifying circuit for increasing the voltage produced by saidmicrophone,

4. a light emitting device connected to said microphone, said powersource, and said amplifying circuit for projecting a light beam ofvariable intensity,

b. a receiving unit including:

1. a light responsive sensor implanted on the promontory in the area ofthe oval window, said light emitting device and said light responsivedevice being in substantial alignment with one another and on oppositesides of the opaque ear drum,

2. said sensor producing a variable voltage proportional to theintensity of the light beam falling thereupon,

3. amplifying means for increasing the voltage produced by said lightresponsive sensor, and

4. conducting means to lead the variable voltage produced by said sensorand said amplifying means to the area of the oval window to electricallystimulate same.

26. An implanted hearing aid for the treatment of tinnitus comprising:

a. a transmitting unit encased in a housing and positioned within theear canal, said transmitting unit including:

1. a miniature microphone for producing a variable voltage proportionalto the sound striking same,

2. a power source for energizing said microphone,

3. an amplifying circuit for increasing the voltage produced by saidmicrophone,

4. a transmitting coil operatively connected to said microphone, saidpower source, and said amplifying circuit for radiating anelectromagnetic field of variable intensity,

b. a receiving unit implanted in the mastoid bone surrounding the earcanal including:

1. a second miniature microphone responsive to the electromagnetic fieldradiated by the transmitting for producing a variable voltage,

2. a power source for energizing the second microphone, and a 3.crystalline device that vibrates in response to the voltage appliedthereto by the second microphone, the vibrations being conducted throughthe mastoid bone to the inner ear to stimulate the auditory nerve.

1. An implantable, sound powered hearing aid comprising: a. transducermeans positioned interiorly of the ear drum in proximity to the ovalwindow within the middle ear cavity, b. said transducer means beingpressure sensitive so as to generate a variable voltage output inresponse to the application of pressure thereto, c. stylus means securedto either the hammer, anvil or stirrup of the ossicle bone chain locatedin the middle ear cavity in operative relationship to said pressuresensitive transducer means, d. said stylus means being pressed againstsaid transducer means by the ossicle bone chain with a variable forcewhen sound strikes the ear drum to thereby produce a variable voltage,and e. conducting means to lead said variable voltage to the area of theoval window to electrically stimulate same.
 2. a power sourCe forenergizing the second microphone, and a
 2. a power source for energizingsaid microphone,
 2. The hearing aid as defined in claim 1 furtherincluding a piezoelectric crystal positioned in the area of the ovalwindow, said conducting means impressing said variable voltage upon saidcrystal to cause same to vibrate and thus stimulate the auditory nerve.2. a power source for energizing said microphone,
 2. said sensorproducing a variable voltage proportional to the intensity of the lightbeam falling thereupon,
 2. conducting means implanted in the mastoidbone to lead the variable voltage received by said coil to the area ofthe oval window to electrically stimulate same.
 2. a stylus connected tosaid diaphragm,
 2. a power source for energizing said microphone,
 3. anamplifying circuit for increasing the voltage produced by saidmicrophone,
 3. an amplifying circuit for increasing the voltage producedby said microphone,
 3. amplifying means for increasing the voltageproduced by said light responsive sensor, and
 3. crystalline device thatvibrates in response to the voltage applied thereto by the secondmicrophone, the vibrations being conducted through the mastoid bone tothe inner ear to stimulate the auditory nerve.
 3. a pressure sensitivetransducer for producing a variable voltage in response to theapplication of pressure thereto, said stylus being positioned inoperative relationship to said transducer,
 3. an amplifying circuit forincreasing the voltage produced by said microphone,
 3. The hearing aidas defined in claim 1 further including a diode positioned in the areaof the oval window, said conducting means leading said variable voltageto said diode which rectifies same into pulsating D.C. voltage and thusstimulates the auditory nerve.
 4. The hearing aid as defined in claim 2further including an amplifying circuit connected between said pressuresensitive transducer means and said piezoelectric crystal, saidamplifying circuit amplifying the variable voltage produced by saidtransducer means before said voltage is impressed upon said crystal. 4.a light emitting device connected to said microphone, said power source,and said amplifying circuit for projecting a light beam of variableintensity, b. a receiving unit including:
 4. a transmitting coiloperatively connected to said microphone, said power source, and saidamplifying circuit for radiating an electromagnetic field of variableintensity, and b. a receiving unit including:
 4. said stylus beingpressed against said transducer when the transmitting moves relative tothe receiving means as sound energy strikes the ear drum to therebyproduce a variable voltage, and c. conducting means to lead saidvariable voltage to the area of the oval window to electricallystimulate same.
 4. a transmitting coil operatively connected to saidmicrophone, said power source, and said amplifying circuit for radiatingan electromagnetic field of variable intensity, b. a receiving unitimplanted in the mastoid bone surrounding the ear canal including: 4.conducting means to lead the variable voltage produced by said sensorand said amplifying means to the area of the oval window to electricallystimulate same.
 5. The hearing aid as defined in claim 2 furtherincluding an auxiliary power supply, connected to said piezoelectriccrystal, to impress its voltage thereupon.
 6. The hearing aid as definedin claim 5 further including a tuning circuit connected between saidpressure sensitive transducer means and said piezoelectric cryStal andin operative relationship to said power supply, said tuning circuitadjusting the frequency at which said crystal will vibrate.
 7. Thehearing aid as defined in claim 5 further including recharging means forsaid auxiliary power supply, said recharging means comprising a buttonunder the skin of the wearer of the hearing aid, a stylus secured tosaid button, and a pressure sensitive transducer means situated inoperative relationship to said transducer means, said transducer meansconnected to said auxiliary power supply to supply a variable voltagethereto, said button being manually depressed to press the stylusagainst the transducer means whenever said auxiliary power supplyrequires recharging.
 8. The hearing aid as defined in claim 2 whereinsaid stylus means comprises a piezoelectric bar with a pin extendingoutwardly therefrom.
 9. The hearing aid as defined in claim 8 whereinsaid piezoelectric bar produces a variable voltage as said bar isstressed when sound striking the ear drum is transmitted through theossicle bone chain, and circuit means for amplifying the variablevoltage before applying same to the oval window area.
 10. The hearingaid as defined in claim 1 wherein the transducer means are held in arectangular package, said package being positioned in the opening of thestapes of said ossicle bone chain with one corner of the package bearingagainst the footplate of the stapes.
 11. The hearing aid as defined inclaim 1 further including a resilient fluid filled sack interposedbetween the ossicle bone chain and the area of the oval window and apiezoelectric crystal disposed thereupon, said conducting meansimpressing said variable voltage produced by said pressure sensitivedevice upon said crystal which vibrates atop the sack and transmits saidvibrations therethrough to the area of the oval window.
 12. The hearingaid as defined in claim 11 further including a collar situated atop saidtransducer means, said collar engaging the free end of the anvil of theossicle bone chain.
 13. The hearing aid as defined in claim 1 whereinsaid transducer means and said stylus means are slipped between thejoint formed by the anvil and stirrup of the ossicle bone chain.
 14. Animplanted hearing aid comprising: a. a transmitting unit encased in ahousing and positioned within the ear canal, said transmitting unitincluding:
 15. The hearing aid as defined in claim 14 further includinga piezoelectric crystal positioned in the area of the oval window, saidconducting means impressing said variable voltage upon said crystal tocause same to vibrate and thus stimulate the auditory nerve.
 16. Thehearing aid as defined in claim 14 further including a diode positionedin the area of the oval window, said conducting means leading saidvariable voltage to said diode which rectifies same into pulsating D.C.voltage and thus stimulates the auditory nerve.
 17. An improved hearingaid comprising: a. transmitting means secured to the inner surface ofthe eardrum in the area of the junction defined by the hammer and theear drum, said transmitting means radiating magnetic waves into themiddle ear cavity, b. receiving means situated within the middle earcavity on the promontory in the area of the oval window, said receivingmeans including:
 18. The hearing aid of claim 17 wherein thetransmitting means is a permanent magnet.
 19. The hearing aid of claim17 wherein the transmitting means is a fragment of phosphor.
 20. Thehearing aid as defined in claim 17 wherein the transmitting means is aradioactive isotope.
 21. The hearing aid as defined in claim 17 whereinthe magnetically responsive means is a field-effect transistor gate. 22.The hearing aid as defined in claim 17 wherein the magneticallyresponsive means is a Hall-effect element.
 23. The hearing aid asdefined in claim 17 further including a piezoelectric crystal positionedin the area of the oval window, said conducting means impressing saidvariable voltage upon said crystal to cause same to vibrate and thusstimulate the auditory nerve.
 24. The hearing aid as defined in claim 17further including a diode positioned in the area of the oval window,said conducting means leading said variable voltage to said diode whichrectifies same into pulsating D.C. voltage and thus stimulates theauditory nerve.
 25. An implanted hearing aid comprising: a. atransmitting unit encased in a housing and positioned within the earcanal, said transmitting unit including:
 26. An implanted hearing aidfor the treatment of tinnitus comprising: a. a transmitting unit encasedin a housing and positioned within the ear canal, said transmitting unitincluding: